Metabolites of arachidonic acid (AA), the eicosanoids, may be important in regulation of renal blood flow and plasma volume, thus influencing blood pressure. The role of these oxygenated metabolies in the rat, which is extensively used in hypertension studies, is however, uncertain. Our long-term objective is to better understand how cyclooxygenase- and lipoxygenase-derived products of AA may influence rat renal hemodynamics and experimental hypertension. Studies utilizing the autoperfused rat kidney will examine the pharmacological effects of prostaglandins (PG), their precursors and lipoxygenase-derived products on renal blood flow. The influence of the endogenously-formed AA products will be examined in similar studies. Their interaction with hormone-induced changes in renal blood flow will be examined using cyclooxygenase inhibitors and essential fatty acid-deficient (EFAD) animals. Experiments are included to define which PG and/or lipoxygenase-derived products are released in response to vasoconstrictor agents. A combination of high performance liquid chromatographic and radiometric methods will be employed for these measurements. The mechanism of sodium-induced regulation of lipases which control AA hydrolysis and subsequent metabolism in the rat renal papilla will be studied using intact papillary tissue prelabelled with AA. The participation of phospholipase C and diglyceride lipase in these events will be studied. Similar studies will determine whether defects in the response of the papilla to sodium may contribute to hypertension in the Dahl "S" rat. The influence of EFA-deficiency on the development of hypertension in the Dahl genetic salt model of hypertension will also be studied.